THE scientific staff of the Zeiss firm have of late I years devoted much attention to the theory of binocular instruments, and to the development of methods of measurement depending on stereoscopic ...

WE have received a copy of a brochure entitled “Stereoskopisches Sehen und Messen” (pp. 40, price 1 mark), by Carl Puifrich. This is the German version, or rather original, of the article “Stereoscope ...